Moisture tester

Abstract

A continuous flow moisture tester includes first and second electrodes defining a capacitive-type test cell. The first electrode comprises a generally cylindrical tube of electrically conductive material, and the second electrode comprises a generally planar body of electrically conductive material disposed adjacent an inner wall of said first electrode member to define a substantially unobstructed passageway between the electrode members. Material carrying members are connected at an inlet and outlet of the passageway for providing a substantially constant flow of material therethrough and for maintaining the passageway substantially evenly filled with flowing material. An electrical circuit is connected with the test cell for producing a signal corresponding to the moisture content of the material flowing therethrough. The circuit is arranged for producing the above-described signal substantially independent of the density of the material or any variations therein, and in accordance with the electrical properties of the material-filled capacitive test cell.

The invention is claimed as follows: 
     
       1. A moisture tester for continuously measuring the moisture content of a material flowing therethrough, comprising: a first electrode member comprising a generally cylindrical tube of electrically conductive material, a second electrode member comprising a generally planar body of electrically conductive material disposed inside of said first electrode member closely adjacent an inner wall thereof and electrically isolated therefrom, said electrodes defining a capacitive test cell having a substantially unobstructed passageway between the electrodes, said tester further including material carrying means connected with said passageway for providing a substantially even flow of material therethrough and for cooperating with said passageway to maintain said passageway substantially evenly filled with said flowing material, and circuit means electrically connected with said capacitive test cell for producing signal means corresponding to the moisture content of said material flowing therethrough, in accordance with electrical properties of the material-filled capacitive test cell. 
     
     
       2. A moisture tester according to claim 1 wherein said cylindrical tube comprising said first electrode includes a top inlet port and a bottom outlet port, respectively, and said second electrode member further includes a section extending between said planar body and said closely adjacent inner wall and sloping toward said inlet port, for directing said material to be tested from said inlet port through said unobstructed passageway. 
     
     
       3. A moisture tester according to claim 2 wherein said material carrying means includes chute means positioned adjacent said inlet port for delivering a supply of material thereto, and screw auger means connected with said outlet port for carrying said material away therefrom at a predetermined rate for adapting said moisture tester for moisture measurement of low density, fine ground materials. 
     
     
       4. A moisture tester according to claim 2 wherein said material carrying means include chute means connected with said inlet port for delivering a supply of material to be tested thereto and restricter cone means connected with said outlet port for restricting the flow of material therethrough to a predetermined rate, adapting said tester for moisture measurement of readily flowing granular material. 
     
     
       5. A moisture tester according to claim 2 wherein said material carrying means includes screw auger means connected with said inlet port for providing material thereto at a predetermined rate and a closure member attached to said outlet port and including means yieldably biasing said closure member thereagainst, for maintaining said test cell substantially filled at said predetermined flow rate of said screw auger means, adapting said tester for moisture measurement of fibrous material. 
     
     
       6. A moisture tester according to claim 1 wherein said circuit means includes means for producing said signal means corresponding to the moisture content of said material substantially independent of the density of said material and of variations therein. 
     
     
       7. A continuous flow moisture tester comprising: a first electrode member of electrically conductive material, a second electrode member of electrically conductive material disposed in a predetermined orientation with respect to said first electrode member for defining a substantially unobstructed, open-ended passageway enclosed by said first and second electrode members, said first and second electrode members being electrically isolated to form a capacitive test cell, material carrying means connected with said test cell for providing a substantially even flow of material therethrough and for maintaining said test cell substantially filled with said flowing material, and circuit means connected with said capacitive test cell for providing signal means corresponding to the moisture content of said material flowing therethrough substantially independent of the density thereof or variations in said density and in accordance with the electrical properties of said material-filled capacitive test cell and wherein said circuit means includes oscillator means, fixed phase shift means connected with said oscillator means, controlled phase shift means, said capacitive test cell being electrically connected in a test network connected between said oscillator means and said controlled phase shift means, phase detector means connected to said fixed and to said controlled phase shifting means and amplifier means connected with said phase detector means, an output of said amplifier means being connected with said controlled phase shift means for maintaining the phase shift provided thereby at a substantially 90° phase angle difference with the phase shift provided by said fixed phase shift means for producing an output signal from said amplifier means substantially proportional to the loss tangent of the material being tested. 
     
     
       8. In a continuous flow moisture tester, the combination comprising: a first electrode member comprising an open-ended tube of electrically conductive material, a second electrode member comprising a sheet of electrically conductive material disposed inside of said first electrode member for defining therewith a capacitive test cell, and means holding said second electrode member closely adjacent to and at least partially abutting an inner wall segment of said tube and electrically isolated therefrom to define a single substantially unobstructed passageway between the second electrode and the remainder of the inner wall of the tube, said passageway comprising a major portion of the interior volume of said tube for the unobstructed flow of material therethrough, said tester further including material carrying means connected with said passageway for providing a substantially even flow of material therethrough and for cooperating with said passageway to maintain said passageway substantially evenly filled with said flowing material, and circuit means electrically connected with said capacitive test cell for producing signal means corresponding to the moisure content of said material flowing therethrough, in accordance with electrical properties of the material-filled capacitive test cell.